Fluid metering or transfer rollers, commonly referred to as "anilox rollers", are used in the printing industry to transfer measured amounts of printing ink onto printing plates. The surface of anilox rollers is engraved with an array of closely spaced, shallow depressions referred to as "cells". Ink is absorbed into the cells from fountain rollers turning within an ink bath. The transfer surface of the anilox roller is scraped with a doctor blade to remove excess ink. The ink remaining on the anilox roller is that contained within the cells. The plate cylinder transfers ink picked up from the anilox roller to a web of material, either plastic or paper, onto which the desired image is imprinted.
The anilox roller is cylindrical and may be constructed in various diameters and lengths, containing cells of various sizes and shapes. The volumetric capacity of an anilox roller is established during manufacturing and is dependent upon the selection of cell size, shape and number of cells per unit area. Depending upon the intended application, the cell pattern may be fine (many small cells per square inch) or coarse (fewer larger cells per squarre inch). Anilox rollers having high cell density are used for high-quality printing and rollers having the largest cells are used in non-printing applications such as the application of glue or paint.